This invention is directed to a sprinkler system, more specifically a sprinkler system coupled with a system aimed at minimizing the effect of wind during watering.
Water resources are very important to humans and ecosystems. Only 2.5% of the Earth's water is freshwater, and of which 98.8% is in ice and groundwater, and less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere. About 70% of the freshwater used by humans goes to irrigation and agriculture to ensure enough food is produced. In recent years, many developing countries are facing with water crisis. In the USA, the governor of California declared mandatory water restrictions last year aiming to reduce the urban water usage by 25% for the first time ever.
For obvious reasons and to make a contribution to the sustainable management of water resource, it is highly desirable for the irrigation and agriculture industry to find better ways to use water more efficiently. Currently most underground sprinkler systems are comprised of heads that can be adjusted for a fixed water flow rate resulting in a fixed radius coverage area. As the radius of coverage is constant through the spray pattern, multiple sprinkler heads must be used to provide complete lawn coverage. In order to provide proper water coverage with a fixed spray pattern, sprinkler manufacturers recommend “Head to Head Coverage” which requires multiple heads per area and results in overlapping watering patterns, creating substantial water wastage and loss.
Patent application WO2015157844 disclosed a new nozzle head design that allows a constantly variable flow throughout its rotation. The sprinkler heads taught are said to be capable of delivering uniform coverage such that the need for overlapping spray areas is eliminated, resulting in significant water savings as well as the saving in water pipe construction. The ability to have one adjustable flow head greatly simplifies installation by eliminating the need for multiple heads and piping normally required within a single area.
However, the installation and parameter setting of this kind of sprinkler system require a lot of effort and experience, and the ultimate performance including the water coverage and precipitation uniformity are unknown until a field test is conducted. On the other hand, the water coverage and uniformity are vulnerable to the effects of wind, the performance of any sprinkler system usually deteriorates quickly when it is exposed to wind.
Despite known sprinkler systems none have incorporated a system to take into account wind on the water being sprayed. The inventors of the present invention have developed a novel system to be coupled with a sprinkler system which greatly overcomes the wind effect on sprayed water under normal and reasonable watering conditions.
The inventors have developed a novel platform which can not only simulate and visualize the overall spraying process for complex lawn shape, but can also provide a solution to shift (minimize) the wind effect under various windy conditions. The platform can be used to facilitate the sprinkler system design, test system performance under windy condition, and generate the wind effect shifting database. The design started with mathematical modelling of droplet dynamic, the droplet movement from a nozzle was simulated.
According to an aspect of the present invention, there is provided a system for use in conjunction with at least one sprinkler, wherein said system comprises:
Preferably, the information relating to a wind comprises: wind speed and wind direction
According to a preferred embodiment, the processor further comprises instructions for manipulating the water output from said at least one sprinkler through incorporation of at least one algorithm used to calculate a value.
According to an aspect of the present invention, there is provided a system for use in conjunction with at least one sprinkler, wherein said system comprises:
Preferably, the wind detector is an anemometer. According to another preferred embodiment, the anemometer is a vane anemometer. Preferably also, the wind detector is adapted to wirelessly relay information to the processor.
According to a preferred embodiment, the processor receives the information from the wind detector and uses a pre-determined value corresponding to an instruction to modify the sprinkler spraying program. Preferably, the pre-determined value corresponding to an instruction is related to the information obtained from the wind detector.
According to a preferred embodiment, the wind detector is adapted to wirelessly relay information to the processor, wherein the processor further comprises a database for storing data representing values obtained through the performing of at least one algorithm, wherein said value is used for manipulating the water output from said at least one sprinkler.
Preferably, the sprinkler is of the single head rotary type.
According to a preferred embodiment, the system further comprising a manifold fluidly connected to a water supply via a flow control valve, wherein said manifold is operated by instructions from a controller.
Preferably, the controller is a computer.
According to a preferred embodiment, the value calculated corresponds to at least one of: droplet diameter; spray speed; spray angle etc.
According to another aspect of the present invention, there is provided method of spraying an area requiring watering under windy conditions, wherein said method comprises:
Preferably, the method further comprises:
Preferably also, said processor receives the information from the wind detector and uses a pre-determined value corresponding to an instruction to modify the sprinkler spraying program. Preferably, the pre-determined value corresponding to an instruction is related to the information obtained from the wind detector.
According to a preferred embodiment, the wind detector is adapted to wirelessly relay information to the processor, wherein the processor further comprises a database for storing data representing values obtained through the performing of at least one algorithm, wherein said value is used for manipulating the water output from said at least one sprinkler. Preferably, the method further comprises the use of at least one moisture sensor to evaluate the soil moisture and to evaluate water precipitation from a spraying program, wherein said moisture sensor is adapted to relay moisture information to the processor. Preferably also, the processor uses the moisture information in its algorithm to modify the spraying program.
The invention may be more completely understood in consideration of the following description of various embodiments of the invention in connection with the accompanying figure, in which:
The platform developed can be used to facilitate the sprinkler system design, test system performance under windy condition, and generate the wind effect shifting database. Starting with mathematical modelling of droplet dynamic, the droplet movement from a nozzle was simulated. The basic principle of the platform is illustrated in details accompanied by some simulation results. Particularly, the wind effect is studied by using the example of square lawn, and provide the shifting solution for different cases. A wind shifting algorithm is presented in details. Given the irrigation range, droplet distribution and wind condition, the proposed algorithm is capable to achieve optimal water coverage and uniform precipitation distribution by counteracting the wind effect.
The modelling of droplet dynamic has been studied by several authors. Lima (J. De Lima, P. Torfs, V. Singh, A mathematical model for evaluating the effect of wind on downward-spraying rainfall simulators, Catena 46 (4) (2002) 221-241.) investigated the mathematical model for a single droplet for a downward-spraying rainfall simulator.
Lorenzini (G. Lorenzini, Simplified modelling of sprinkler droplet dynamics, Biosystems Engineering 87 (1) (2004) 1-11.) proposed a simplified modelling for droplet dynamics without considering the wind effect.
Salvador (R. Salvador, C. Bautista-Capetillo, J. Burguete, N. Zapata, A. Serreta, E. Playa'n, A photographic method for drop characterization in agricultural sprinklers, Irrigation science 27 (4) (2009) 307-317.) proposed a photographic method to determine the droplet diameter.
Moita (R. D. Moita, H. A. Matos, C. Fernandes, C. P. Nunes, M. J. Pinho, Dynamic modelling and simulation of a heated brine spray system, Computers & Chemical Engineering 33 (8) (2009) 1323-1335.) investigated the dynamic modelling for a heated brine spraying system.
Conti (A. Conti, D. DeWrachien, G. Lorenzini, Computational fluid dynamics (cfd) picture of water droplet evaporation in air, Irrigation and Drainage Systems Engineering 2012) studied the water droplet evaporation in the air based on computational fluid dynamics.
To arrive at the platform designed, the following hypotheses were adopted: the forces applied to the system were weight and frication; the buoyancy was ignored; the evaporation was not considered; and the droplet keeps a spherical shape during the flight, thus its volume does not change.
In practice, the buoyancy has negligible effect to the droplet movement, thus was also neglected. The variables and parameters used in this study are listed in the following Table 1.
With the assumptions above, and according to Newton's second law of motions, the mathematical model can be described as the following:
where the droplet mass m is defined as
m=4/3πr3=⅙πd3,
and the drag friction coefficient is denoted by k which is given by k=ψρpad2.
A fast numerical solver using Runge-Kutta methods is implemented in the platform to compute the solution for the system of nonlinear ordinary differential equations (ODE). In a sprinkler system, one of the most important characteristic is the size of droplet that the nozzle can generate. For a constant spraying velocity, the different droplet diameter can result on different spraying distance. Similarly, given a constant droplet diameter, the variant spraying velocity will generate variant spraying distance. Thus we begin with analyzing the relationship between the droplet diameter, spraying velocity and spraying distance by testing a 2D single droplet spraying case. Under the windless condition, in
Based on the various calculations the droplet distance would only be increased by about 2 times, from 55 m to 105 m as the flow speed vo is increased from 100 m/s to 1000 m/s. The trajectory of a single droplet with fixed initial speed=120 m/s for droplet with diameter d=[0.002 0.004 0.008 0.016] m in
From
Through the platform developed, it was possible to simulate a conventional sprinkler system with circular coverage. In
Actually, besides the conventional sprinkler pattern, the proposed platform was determined to properly simulate the sprinkler system with more complicated design discussed in the next section.
The platform developed was shown to be capable of simulating a sprinkler system with the following features:
With these features, it is clear that the intelligent sprinkler system according to an embodiment of the present invention is superior to a conventional sprinkler system in terms of the following aspects:
As an illustration, assuming a rectangular lawn with the dimension of 80 m×40 m, where the nozzle is placed on the boundary of the lawn as shown in
The basic idea to achieve optimum water coverage is that first the rectangular area is divided into n pies, where n is a user-defined value, then for each pie, the required velocity is computed such that the spray precisely reach the target distance. To just cover the shape of the lawn, the target distances are just the boundary of the lawn. As would be clear to the person skilled in the art, the target distances are determined by the contour of the lawn. To find the accurate required flow velocity to reach certain target distance, the characteristic curve is used. The characteristic curve is a function that provides the information regarding the spraying distance vs initial flow velocity for droplet at certain diameter. Once the droplet diameter is selected and the elevation angle, the characteristic curve is determined. The characteristic curve for the droplet with d=0.01 m is shown in
The x and y axis in
In fact, for a typical sprinkler system, the spray generated by the nozzle contains droplets with various diameters.
Besides the conventional rectangle lawn, the platform is capable of simulating sophisticated spraying process for lawn with more complex contours. In any case, the location of the sprinkler can be selected to be either inside the lawn perimeter or on the boundary of the lawn.
By assigning multiple target distances to the sprinkler system, and let each target distance keep same proportion at each angle, the multiple round spraying process can be simulated. As shown in
Conventionally, the spraying process, is from outer round to inner round, and the distance between each round is called pull back amount. For the simulation process conducted and reported in
The platform provides a high degree of freedom to the users, and most variables in the simulation process can be set by users via a Graphical User Interface.
The spraying process simulation described previously is based on droplet with a constant diameter. In reality, the spray jetted from nozzle consists of hundreds of thousands of droplets, and the diameters of these droplets are different. Therefore, to estimate the overall precipitation distribution, the estimate of droplet diameter distribution is needed. Given a certain droplet diameter distribution, the spraying pattern of droplets with various diameters can be computed, such that the corresponding water volume can be estimated. Obviously, the droplet diameter distribution is an important characteristic of the nozzle, and for given nozzle, its diameter distribution can be obtained from field test or experiments. As a general assumption of the droplet diameter distribution, the normal distribution is used in the following work. According to the definition, the percentage of droplet with certain diameter in terms of total water volume is given by
where μ is the mean value of the droplet, σ is the variance of the droplet. Let x axis be the droplet diameter, and y axis denotes the water volume percentage, then the droplet diameter distribution with mean diameter g=0.01 m and standard deviation σ=0.002 m is given in
Assuming the water volume used in each sweep is C, then the total water volume of droplet with the diameter d is given by
N(d)=C*f(d|μ,σ).
If the mean droplet diameter is p=0.01 m, σ=0.002 m, and the range of the droplet diameter is [0.001, 0.002, . . . , 0.019, 0.020] m, then the droplet trajectory of the droplet with each diameter is denoted by the light narrow lines in
Considering now the precipitation distribution result can be effectively estimated. In
Considering the wide range of the droplet diameter distribution, the selection to find the required flow velocities and corresponding angles was based on the mean droplet diameter, thus the choice of target distance was very important for achieving a uniform precipitation distribution.
Preferably, the system provides an algorithm called divider lines method to automatically compute the optimal pull back amount for given number of pull back. All the boundary lines in the following simulations were computed by the divider lines method.
Considering the wind effect is now incorporated into the simulation. Consider the lawn of
In the first wind effect simulation the wind is from west to east having an angle of 30 degree between wind direction x-axis.
For the simulation results in
where i denotes all the blocks within and outside the lawn, and target, is defined as 5,
Obviously, the MSE measures not only the uniformity inside the lawn, but also the water wasted outside the lawn. It is well known that the entropy can be used to measure the amount of order or disorder of a system, the higher the entropy of a system, the more ordered the system is. A person skilled in the art will understand that for the precipitation case, the higher the entropy after he spraying, the more uniform the lawn is. The Entropy is defined as 6:
where i denotes all the blocks within the lawn, pi is the water proportion in block i. By using MSE and entropy, the wind effect shown in
From Table 2, it can be seen that as the wind speed increase, the MSE increases and Entropy decreases, showing the wind effect severity from MSE and Entropy aspects. As mentioned before, the proposed platform provides a big degree of freedom for the simulation. In
To introduce the idea of wind shifting technology, one considers the lawn in the shape of square as in
Assuming a fixed flow velocity=55 m/s, the spray can accurately reach the lower right corner from the center under the windless condition. Assuming there are five different wind conditions, where the wind speed w=4.92 m/s, and the wind directions are indicated by arrows in
By using the counteraction solutions in Table 3, the wind effect can be quite effectively counteracted as shown in
In the next section we will illustrate how to find the required flow velocity as well as corresponding angles under the wind conditions.
Denoting the target spraying distance as To. According to the algorithm in the previous section, the required velocity vo and spraying angle vo without wind can be computed from the lawn contour information.
To counteract the wind effect, the optimal flow velocity and angle are studied as the following:
v
i
=v
i-1
+Δv
i-1 (7)
γi=γi-1+Δγi-1, i=1,2, . . . (8)
where Δγi-1 and Δvi-1 are the ith searching step size of flow speed and angle, vi and γi are the updated speed and angle after ith correction. To find the appropriate v and y such that the wind effect can be efficiently counteracted, define the actual dropping point of droplet after i correction as T(vi, γi), then the spraying error SE after nth correction can be defined as the distance between T(vn, yn) and T0:
SE(vi,γi)=√{square root over ((Tx(vi,γi)−T0x)2+(Ty(vi,γi)−T0y))2)}. (9)
Under wind speed w and wind direction β, the appropriate velocity and angle can be found by minimizing the target function (9) until the error se is less than user custom threshold value.
Although an optimal solution can be reached by a method of traversal under a specified precision, it's time-consuming and impossible to provide a real-time result on an embedded sprinkler system.
Preferably, one uses a more efficient algorithm as shown in
Using the adaptive searching step, the global minimum can always be reached, such that the spraying error se=0. However, in practice the instruments can never be exactly accurate, and one does not always require a completely accurate shifting as water can move on the ground within a certain range. On the other hand, the higher precision wind shifting compensation consumes more time, which limits the real-time implementation of the algorithm, thus the appropriate threshold can be set according to the computing power as well as the precision of the equipment.
In light of this, the wind shifting algorithm is applied with different threshold value, and the corresponding time is reported in Table 5 and
1Measured by 1000 test cases using Matlab code on labtop with Intel i7-5500U processor.
Based on the wind shifting algorithm set out above, the algorithm was applied to a 30 m×30 m lawn as in the
The results before and after shifting are reported in
From Table 6 and 7, it can be seen that the wind shifting algorithm provides very good shifting results in terms of MSE and Entropy. Particularly, in some cases the precipitation after shifting is even more uniform than the case without wind: when the wind speed w=5 m/s, the MSE without shifting is 2.13 and that with shifting is 1.07, which is a significant improvement. It should also be noted that the shifting results are very stable, for instance, the Entropy after shifting is always 4.82 in both cases.
To achieve the best wind shifting effect, the wind condition should ideally be updated in real time. However, it is quite normal that the wind measuring apparatus are not accurate and contain certain delays. Therefore, sensitivity analysis is essential to test the performance of the shifting algorithm when certain errors are included in the measured wind. To do this, a constant measured wind is used such that the wind shifting parameter unchanged, and let the actual wind change, then test if the performance of wind shifting still be good, or it will deteriorate quickly.
Assuming that the measured wind is 5 m/s, and the actual wind is from 2 m/s to 8 m/s, which denotes about 60% measured error in terms of wind speed. The shifting results are reported in
Similar to the previous cases, the precipitation uniformity is quantified when the measure error exists in terms of MSE as well as Entropy as listed in following Table 8
The shifting error vs. the wind measuring error was reported in terms of wind speed and wind angle for the measure wind w=6 MPH and w=11 MPH.
The wind shifting algorithm can be used to calculate the required flow velocity and spray angle to reach any target point on a predetermined lawn. To cover the whole lawn, different target distances td are set up for each round of spraying.
One must consider how to set up the target distances for each round in order to reach a good distribution uniformity and compare three kinds of different methods.
The most straightforward way to set up target distances is to use an arithmetic progression. An example is shown in
The third method is divider lines method. The lawn is divided into n+1 area equal parts, and use the n divider lines as the target distances. In
To determine the value of n, one divides the desired total irrigation amounts by the water volume per round. Given the value of n, one can use the above-mentioned method to reach a good water distribution. The MSE and Entropy for the three methods mentioned above are reported in the following Table 9. It can be seen that the divider lines method provides the smallest MSE and the largest Entropy, thus it is the best method of the three to automatically select the target distance.
According to a preferable embodiment of the present invention, one can apply the simulation platform into a real application by computing the shifting parameters in real time.
According to another preferable embodiment of the present invention, one can apply the simulation platform into a real application by computing the shifting parameters in advance and storing those in a database. Upon use, the corresponding required flow speed as well as required angles are extracted from the database to counteract a measured wind.
The implementation of the first method is quite straightforward. However, the implementation of the database to achieve the wind shifting is more a more efficient way when the computing power is limited. Assume the need to generate a database for a lawn, where the wind speed can be [1, 2, 3, 4] MPH, the wind direction can be [10, 20, 30, 40] degree with x-axis, and the lawn is divided in the n pies, then the database which includes the required flow speed and spraying angle can be stored as a 3D matrix as in
Each bar in
For a multiple pull back spraying process, the proportion of the pull back amount can also be included in the database in the format of a 4D matrix. The platform includes a Graphic User Interface (GUI) to generate the required database.
According to an embodiment of the present invention, the sprinkler apparatus used in conjunction with a system compensating for wind effect comprises: (a) a base housing configured to confiningly receive a pressurized water flow; (b) a nozzle housing coupled to the base housing, the nozzle housing sized to slidingly couple with the base housing to pop-up into an operating position or retract into a nested position; (c) an upper nozzle assembly positioned at a top end of the nozzle housing, the upper nozzle assembly comprising a rigid outer frame and a resilient inner nozzle positioned therein, the diameter of the inner nozzle being smaller than the rigid outer frame to provide space for the inner nozzle to distend to a maximum orifice size determined by the circumference of the outer frame, the resilient inner nozzle responsive to the rate of pressurized water flow to distend up to the maximum orifice size to vary the wetted radius of discharged water from the upper nozzle assembly; (d) a lower nozzle assembly positioned below the upper nozzle assembly at the top end of the nozzle housing, the lower nozzle assembly comprising a vertical slit-shaped aperture through which water is discharged in a curtain effect; and (e) a flow control valve assembly fluidly coupled to the base housing to controllably supply the pressurized water flow: wherein the upper and lower nozzle assemblies together achieve a substantially uniform elliptical spray pattern.
As a person skilled in the art would know, the spray pattern of a sprinkler apparatus is known to have inconsistencies in uniformity. Inconsistencies in spray pattern uniformity can result in over-watering and/or under-watering of the water receiving area leading to inefficient irrigation. To minimize such inconsistencies, uniformity of water distribution by a sprinkler apparatus used in the purposes of the present disclosure can be programmably controlled, according to some embodiments, using computer instrumentation programmed to create and implement a spray partem that is designed to compensate for inconsistencies in spray pattern uniformity based on nozzle profile and target precipitation density for the water receiving area. In such embodiments, the rate of flow of the pressurized water supply into and out of the flow control valve assembly and into and out of the pop-up type sprinkler head is modulated to vary the wetted radius of the water projected outward from the sprinkler head with each sweep of the sprinkler, so that the water receiving area is uniformly watered over the geometry of its entire area.
According to a preferred embodiment of the present invention, a sprinkler apparatus used in conjunction with the system according to the present disclosure can comprise computer instrumentation programmed to select a desired target level of precipitation density for the water receiving area; determine the number of sprinkler sweeps needed to achieve the selected precipitation density; pair the number of determined sprinkler sweeps with the selected precipitation density to determine the amount to pull back (i.e., reduce the wetted radius) on each sweep; determine a new flow rate based on the amount of pull back determined; and generate a spray pattern that applies the pulled back flow rates at the calculated rates on each sprinkler sweep to correct the inconsistencies in the uniformity of the spray pattern. In this way, a sprinkler spray pattern can be created that is adjusted with each spray sweep to correct inconsistencies in the uniformity of the spray pattern so that the water receiving area is ideally as optimally uniformly watered as possible (within the limitations of the instrumentation) over the geometry of its entire area.
Another exemplary embodiment of the present disclosure pertains to a method for irrigating an irregularly shaped and/or an asymmetrically shaped water receiving area while enduring winds which affect the optimal water distribution. The method generally comprises: (a) providing a sprinkler system as described above; (b) determining the geometry and irrigation needs of the water receiving area; (c) selectively diverting the water supply to the one or more sprinkler apparatus suitable to the geometry and irrigation needs determined for the water receiving area; (d) positioning the orientation of each of the one or more sprinkler apparatus according to the geometry and irrigation needs determined for the water receiving area; and (e) adjusting the pressurized water flow to each of the one or more sprinkler apparatus according to the geometry and irrigation needs determined for the water receiving area and, optionally, (f) altering the sprinkler head speed through out each sprinkler sweep to correct inconsistencies in the uniformity of the spray pattern. According to further embodiments, the step of adjusting in step (e) comprises optimizing each of the one or more sprinkler apparatus to create a sprinkler spray pattern that is adjusted with sprinkler sweep to correct inconsistencies in the uniformity of the spray pattern, said optimizing comprising: (a) selecting a desired target level of precipitation density for the water receiving area; (b) determining the number of sprinkler sweeps needed to achieve the selected precipitation density; (c) pairing the number of determined sprinkler sweeps with the selected precipitation density to determine the amount to pull back on each sweep; (d) determining a new flow rate based on the amount of pull back determined; and (e) generating a spray pattern that applies the pulled back flow rates at the calculated rates on each sprinkler sweep to correct inconsistencies in the uniformity of the spray pattern.
According to a preferred embodiment of the present invention, the sprinkler system can further include a system controller or other computer instrumentation to synchronize the operation of each sprinkler apparatus in the system. In other preferred embodiments, the controller or other computer instrumentation is programmable for example, following a logic and steps specific to the lawn to be watered. Exemplary components for the controller include a microprocessor, a programmable logic circuit (or “PLC”), an analog control circuit, and electronic components (e.g., transistors, resistors, diodes, etc.) on a circuit board.
According to further embodiments, the system can be programmed to establish a watering program that is activated in response to the environmental conditions of the water receiving area. In such embodiments, for example, the system can comprise sensors for continual monitoring of the conditions of the water receiving area in order to determine whether watering is required, and further to establish the parameters for achieving sufficient watering for the particular water receiving area. According to certain embodiments, the sensors are moisture sensors for continually monitoring the soil to determine when watering is required, how it is watered, and for how long it is watered. For example, the system can be configured to monitor one or more environmental conditions to make this determination, including without limitation, moisture level of the soil, temperature of the soil, solar load on the soil, salinity of the soil, wind measurements, and/or precipitation measurements. Once the system determines that watering is required, the system is activated to water the water receiving area for a predetermined time. Moisture values can continue to be monitored and compared to original values in order to determine water absorption by the soil, and/or achievement of target moisture rates.
According to a preferred embodiment of the present invention, the sprinkler system can comprise computer instrumentation programmed to select a desired target level of precipitation density for the water receiving area; determine the number of sprinkler sweeps needed to achieve the selected precipitation density: pair the number of determined sprinkler sweeps with the selected precipitation density to determine the amount to pull back (i.e., reduce the wetted radius) on each sweep; determine a new flow rate based on the amount of pull back determined; and generate a spray pattern that applies the pulled back flow rates at the calculated rates on each sprinkler sweep to correct the inconsistencies in the uniformity of the spray pattern. In this way, a sprinkler spray pattern can be created that is adjusted with each spray sweep to correct inconsistencies in the uniformity of the spray pattern and thereby further optimize the uniformity of watering the specific water receiving area.
Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the scope of the invention. All such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.
Number | Date | Country | Kind |
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2949767 | Nov 2016 | CA | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CA2017/000250 | 11/24/2017 | WO | 00 |